Front suspension structure for saddle riding type vehicle

ABSTRACT

A front suspension structure includes a head pipe radially internally supporting a shaft portion forming a steering axis such that the shaft portion is rotatable about the steering axis; a front fork connected to a lower end portion of the shaft portion on a lower side of the head pipe, the front fork supporting an axle of a steering wheel; a link member having one end portion connected rotatably on an upper side of a turning member having the shaft portion, and having another end portion connected rotatably on a side of handlebars; the head pipe disposed so as to be separated frontward from a vehicle body frame; and a rocking arm having a front end portion rockably supported by the head pipe, and having a rear end portion rockably supported by the vehicle body frame.

FIELD OF THE INVENTION

This application relates to a front suspension structure for a saddleriding type vehicle.

BACKGROUND OF THE INVENTION

One example of a conventional front suspension structure for a saddleriding type vehicle is disclosed in Japanese Patent Laid-Open No. Hei4-169386 (“JP '386”). This structure supports a steering shaft link,which steerably supports a front fork, and a vehicle body frame by frontand rear end portions of an upper arm portion and a lower arm portioneach extending longitudinally. The steering shaft link is disposed onthe inside in a radial direction of the front fork.

SUMMARY OF THE INVENTION

One problem with the aforementioned structure of JP '386 is that, whenthe front end portions of the upper and lower arm portions are supportedby the steering shaft link on the inside in the radial direction of thefront fork (head pipe) (a type in which the head pipe rotates), thepositions at which the front end portions of the upper and lower armportions are supported are inevitably the upper and lower end portionsof the steering shaft link which end portions project above and belowthe head pipe. Therefore, a degree of freedom of the position at whichthe arm portion is supported is lowered.

Therefore, one objective of the present invention is to increase adegree of freedom of the position at which an arm portion is supportedin a front suspension structure for a saddle riding type vehicle whichstructure supports a steering member by the arm portion rockingvertically.

To achieve this objective, one aspect of the present invention includesa head pipe (12) radially internally supporting a shaft portion (13 b)forming a steering axis (C3) such that the shaft portion (13 b) isrotatable about the steering axis (C3); a front fork (19) connected to alower end portion of the shaft portion (13 b) on a lower side of thehead pipe (12), the front fork (19) supporting an axle (9 a) of asteering wheel (9); and a link member (15) having one end portionconnected rotatably on an upper side of a turning member (13) having theshaft portion (13 b), and having another end portion connected rotatablyon a side of handlebars (8); the head pipe (12) being disposed so as tobe separated frontward from a vehicle body frame (1); a rocking arm (16)having a front end portion rockably supported by the head pipe (12), andhaving a rear end portion rockably supported by the vehicle body frame(1). Accordingly, the front end portion of the rocking arm is supportedby the head pipe on the outside in the radial direction of the shaftportion forming the steering axis. Thus, the position at which therocking arm is supported can be set arbitrarily. Hence, a degree offreedom of the position at which the arm portion is supported can beincreased. In addition, because a turning system of the turning memberand the like and a rocking system of the rocking arm and the like areseparated from each other, the turning system is not readily affected byrocking.

According to a second aspect of the present invention, the rocking arm(16) includes an upper arm portion (17) and a lower arm portion (18)vertically separated from each other, the head pipe (12) is inclinedsuch that an upper side of the head pipe (12) is located more rearwardthan a lower side of the head pipe (12) as viewed from a side, a frontend portion (17 a) of the upper arm portion (17) is in front of thesteering axis (C3) and is supported by a front upper portion of the headpipe (12), and a front end portion (18 a) of the lower arm portion (18)is in a rear of the steering axis (C3) and is supported by a rear lowerportion of the head pipe (12). Accordingly, spaces of the front upperportion and the rear lower portion of the head pipe which spaces arecreated by the inclination of the head pipe can be utilized effectivelyas spaces for supporting the respective front end portions of the upperand lower arm portions. It is therefore possible to make the frontsuspension structure compact and thus shorten an overall length of thefront suspension structure. In addition, because the respective frontend portions of the upper and lower arm portions are distributedlongitudinally, the concentration of force on one part can be prevented.

According to a third aspect of the present invention, the front endportion (17 a) of the upper arm portion (17) and the front end portion(18 a) of the lower arm portion (18) are rockably supported via couplingmembers (34 a, 36 a), respectively, the coupling members (34 a, 36 a)penetrating connecting portions (12 a, 12 b) of the head pipe (12) andextending along a vehicle width direction. Accordingly, the upper andlower arm portions can be supported by the respective coupling membersso as to avoid the head pipe. Therefore the respective front endportions of the upper and lower arm portions can be supported with highrigidity.

According to a fourth aspect of the present invention, the front endportion (17 a) of the upper arm portion (17) and the front end portion(18 a) of the lower arm portion (18) are connected respectively toconnecting portions (12 a, 12 b) of the head pipe (12) rockably aboutcoupling axes (C9, C11) along the vehicle width direction, and at leastone of the coupling axes (C9, C11) is disposed between an upper end anda lower end of the head pipe (12) as viewed from the side. Accordingly,the respective front end portions of the upper and lower arm portionscan be supported on the head pipe compactly.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described with reference to theaccompanying drawings, wherein:

FIG. 1 is a left side view of a front portion of a vehicle body of amotorcycle according to an embodiment of the present invention.

FIG. 2 is a left side view of a front wheel suspension device of themotorcycle.

FIG. 3 is a perspective view of the front wheel suspension device asviewed from an upper left front.

FIG. 4 is a top view of the front wheel suspension device.

FIG. 5 is a sectional view including a section along a rotation axis ofthe front wheel suspension device and a horizontal section of a leftlink member.

FIG. 6 is a sectional view including a section along a first couplingaxis of an upper arm portion of the front wheel suspension device and asection along a second coupling axis.

FIG. 7 is a sectional view including a section along a third couplingaxis of a lower arm portion of the front wheel suspension device, asection along a fourth coupling axis, and a section along a central axisof a connecting portion for connecting a front lower end portion of acushion unit.

FIG. 8 is a sectional view including a section of a connecting portionof an upper end portion of a front fork of the front wheel suspensiondevice along the longitudinal direction of a head pipe and a sectionalong a central axis of a front wheel axle.

FIG. 9 is a left side view showing various axes of the front wheelsuspension device and the like.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will hereinafter be describedwith reference to the drawings. Incidentally, directions such as aforward direction, a rearward direction, a left direction, a rightdirection, and the like in the following description are identical withdirections in a vehicle to be described in the following unlessotherwise specified. In addition, an arrow FR indicating the forwarddirection of the vehicle, an arrow LH indicating the left direction ofthe vehicle, an arrow UP indicating the upward direction of the vehicle,and a lateral center line CL of the vehicle are shown in appropriatepositions in the drawings to be used in the following description.

FIG. 1 shows a front portion of a vehicle body of a motorcycle as anexample of a saddle riding type vehicle. Referring to FIG. 1, a vehiclebody frame 1 of the motorcycle has a front block 2 as a front endportion of the vehicle body frame 1 which front block 2 supports a frontwheel suspension device 10.

A pair of left and right main frames 3 extends rearward and downwardfrom the rear of the front block 2, and a pair of left and rightsub-frames 3 a extends rearward from the rear of the front block 2. Theleft and right main frames 3 are connected to a pivot frame 4 thatsupports a rear wheel suspension device not shown in the figures. Ahorizontally opposed engine 5, for example, is mounted below the frontblock 2, the left and right main frames 3, and the left and rightsub-frames 3 a. A fuel tank 6 is disposed on the front block 2 and theleft and right main frames 3. The front portion of the vehicle body ofthe motorcycle is covered by a front cowl 7 made of a synthetic resin.

Referring also to FIG. 2 and FIG. 3, the front block 2 has a V-shapeprojecting forward and upward as viewed from the side. Connectingportions 2 b to which rear end portions 17 b of an upper arm portion 17to be described later are connected are formed in a front upper endportion of the front block 2. Connecting portions 2 c to which rear endportions 18 b of a lower arm portion 18 to be described later areconnected are formed in the vicinity of a vertical center of the frontblock 2.

Supporting portions 2 d supporting a left side portion and a right sideportion of the engine 5 are formed in a front lower end portion of thefront block 2.

The front wheel suspension device 10 includes a supporting portion 2 a,a handlebar post 11, a head pipe 12, a turning member 13, a rotarymember 14, link members 15, a rocking arm 16, a front fork 19, and acushion unit 20.

Referring also to FIG. 8 and FIG. 9, the front fork 19 is disposed belowthe head pipe 12. The front fork 19 has an upper end portion connectedto a shaft portion 13 b of the turning member 13, and has a lower endportion supporting a front wheel axle 9 a of the front wheel 9 as asteered wheel.

The front fork 19 integrally has a pair of left and right arm portions19 a extending vertically and a cross member 19 b coupling upper endportions of the left and right arm portions 19 a to each other. Theelements of the front fork 19 are each an integral part made ofaluminum, for example. These elements are joined by welding to beintegral with each other.

The left and right arm portions 19 a are arranged on both of the leftside and the right side of the front wheel 9. The cross member 19 b iscurved to the inside in a vehicle width direction in such a manner as tobe along a tread surface at an upper end position of the front wheel 9,and is disposed between the upper end portions of the left and right armportions 19 a. The left and right end portions of the cross member 19 bare joined to the upper end portions of the left and right arm portions19 a.

A connecting portion 19 c to which the shaft portion 13 b of the turningmember 13 is connected is formed in an upper end portion of the crossmember 19 b. An insertion hole 19 h opening in a direction in which theshaft portion 13 b of the turning member 13 extends is formed in theconnecting portion of the cross member 19 b. The shaft portion 13 b ofthe turning member 13 has a maximum diameter at a lower end portionthereof. The shaft portion 13 b is inserted into the insertion hole 19 hfrom an upper end portion of the shaft portion 13 b, and a lower endportion of the shaft portion 13 b and the connecting portion 19 c arejoined to each other by welding in a state in which the lower endportion of the shaft portion 13 b is located in the insertion hole 19 h,whereby the upper end portion of the front fork 19 is fixedly connectedto the shaft portion 13 b of the turning member 13.

Incidentally, a symbol 13 g in the figures denotes a ball bearingretained in an inner circumference of a lower end portion of the headpipe 12.

Connecting portions 19 d to which the front wheel axle 9 a is connectedare formed in lower end portions of the left and right arm portions 19a. An insertion hole 9 h opening in the vehicle width direction isformed in the connecting portions 19 d of the left and right armportions 19 a. In a state of a hub portion 9 d of a wheel 9 c of thefront wheel 9 being held between the connecting portions 19 d of theleft and right arm portions 19 a, a bolt 9 b is passed through theinsertion holes 9 h and an inner circumference of the hub portion 9 d ofthe wheel 9 c, and is screwed and fastened to one end of the front wheelaxle 9 a. An outer circumference of the front wheel axle 9 a is providedwith a pair of left and right side collars 9 j, a pair of left and rightball bearings 9 g adjacent to the insides of the left and right sidecollars 9 j, and a center collar 9 i for securing a distance between theleft and right ball bearings 9 g. Both end portions in the vehicle widthdirection of the front wheel axle 9 a are fixedly supported by the lowerend portion of the front fork 19, and the wheel 9 c of the front wheel 9is rotatably supported by a center in the vehicle width direction of thefront wheel axle 9 a via the left and right ball bearings 9 g.

Incidentally, a symbol 21 a denotes a brake rotor whose inner rotor isfixed to both of a left end and a right end of the hub portion 9 d. Asymbol C1 in the figures denotes the central axis of the front wheelaxle 9 a. A symbol C1L in the figures denotes a perpendicular from thecentral axis C1 to a ground G. A symbol T in the figures denotes atrail.

A brake caliper 21 is supported in the rear of the lower portion (leftand right arm portions 19 a) of the front fork 19. A front fender 22 issupported on the upper portion (cross member 19 b) of the front fork 19via a bolt not shown in the figures.

Referring also to FIG. 2, FIG. 3, and FIG. 9, the supporting portion 2 ais provided on a longitudinal center of the upper end portion of thefront block 2 so as to be inclined rearward with respect to a verticaldirection as viewed from the side. The supporting portion 2 a is forexample provided integrally with the upper front end portion of thefront block 2 made of aluminum. An upper portion of the supportingportion 2 a rotatably (steerably) supports the handlebar post 11, and alower portion of the supporting portion 2 a rockably supports a rearupper end portion 20 b of the cushion unit 20.

Specifically, a shaft portion 11 a of the handlebar post 11 is insertedinto an inner circumference of the upper portion of the supportingportion 2 a, and the supporting portion 2 a rotatably (steerably)supports the shaft portion 11 a. A ball bearing not shown in the figuresis retained in the inner circumference of the supporting portion 2 a. Anupper end portion of the shaft portion 11 a projects above thesupporting portion 2 a. This projecting portion fixedly supports aholder 11 b of the handlebar post 11. A pair of left and rightconnecting portions 2 e to which the rear upper end portion 20 b of thecushion unit 20 is connected is formed in both sides in the vehiclewidth direction of the lower portion of the supporting portion 2 a.

Incidentally, a symbol C2 in the figures denotes the central axis of theshaft portion 11 a. The central axis C2 may hereinafter be referred toas a steering axis. The shaft portion 11 a of the handlebar post 11forms the steering axis C2.

Referring to FIG. 5, the handlebar post 11 forms a V-shape projectingrearward as viewed in a direction along the steering axis C2. Alaterally central portion of the handlebars 8 is fixedly supported onthe holder 11 b of the handlebar post 11. Referring to FIG. 2, the shaftportion 11 a of the handlebar post 11 is rotatably supported by thesupporting portion 2 a, and thereby the handlebars 8 above thesupporting portion 2 a are supported by the handlebar post 11 rotatably(steerably) about the shaft portion 11 a (steering axis C2). Connectingportions 11 c to which a left second ball joint 43 and a right secondball joint 43 to be described later are connected are formed in a leftend portion and a right end portion of the handlebar post 11.

Referring also to FIG. 2, FIG. 8, and FIG. 9, the head pipe 12 isdisposed so as to be separated frontward from the steering axis C2. Thehead pipe 12 is inclined such that an upper side of the head pipe 12 islocated more rearward than a lower side of the head pipe 12 as viewedfrom the side. Specifically, the head pipe 12 forms a cylindrical shape,and is disposed in front of the supporting portion 2 a (front block 2)so as to be inclined rearward with respect to the vertical direction.The head pipe 12 radially internally supports the shaft portion 13 b ofthe turning member 13 rotatably (steerably) about the central axis C3 ofthe shaft portion 13 b. A connecting portion 12 a to which the front endportion 17 a of the upper arm portion 17 is connected is formed in frontof the steering axis C3 and in the front upper portion of the head pipe12 so as to project forward and upward. A connecting portion 12 b towhich the front end portion 18 a of the lower arm portion 18 isconnected is formed in the rear of the steering axis C3 and in the rearlower portion of the head pipe 12 so as to project rearward anddownward.

Incidentally, the central axis C3 of the shaft portion 13 b coincideswith the central axis of the head pipe 12. The central axis C3 mayhereinafter be referred to as a steering axis (turning axis). The angleof the steering axis C3 to the vertical direction is a “caster angle.”The steering axis C3 is offset (separate) frontward from the steeringaxis C2, and forms the shape of a straight line inclined such that anupper side of the straight line is located more rearward than a lowerside of the straight line as viewed from the side. The steering axis C3and the steering axis C2 are parallel to each other in a 1G state inwhich the load of a vehicle weight is applied to the front wheelsuspension device 10 in the figures (which state may hereinafter bereferred to simply as a “1G state”).

Referring also to FIG. 2 and FIG. 5, the turning member 13 is rotatablysupported by the head pipe 12, and is steered about the steering axis C3integrally with the front wheel 9. The turning member 13 includes anupper portion 13 a and the shaft portion 13 b. The upper portion 13 ahas a C-shape whose front portion projects frontward as viewed from theside. The shaft portion 13 b extends along the direction in which thehead pipe 12 extends.

A lower end portion of the upper portion 13 a forms a C-shape opening tothe rear as viewed from a direction along the steering axis C3. Aninsertion hole 13 h into which a positioning pin 13 c is inserted isformed in a front lower end portion of the upper portion 13 a. Aninsertion hole 30 h opening in the vehicle width direction is formed ina rear lower end portion of the upper portion 13 a. In a state of thepin 13 c being inserted in the insertion hole 13 h, a bolt 30 a ispassed through the insertion hole 30 h, and is screwed and fastened to anut 30 b, whereby the lower end portion of the upper portion 13 a isfastened and fixed to the upper end portion of the shaft portion 13 b.

Referring also to FIG. 2, FIG. 4, FIG. 5, and FIG. 9, a cylindricaljournaling portion 13 d extending in the vehicle width direction isformed in an upper end portion of the upper portion 13 a. The journalingportion 13 d is disposed on the upper side of the left and right linkmembers 15 as viewed from the side. The journaling portion 13 d supportsthe rotary member 14 such that the rotary member 14 is rotatablecoaxially with the journaling portion 13 d.

Incidentally, a symbol C4 in the figures denotes the central axis of thejournaling portion 13 d. The central axis C4 may hereinafter be referredto as a rotation axis.

The rotary member 14 is disposed between front end portions of the leftand right link members 15 and the turning member 13. The rotary member14 is disposed in the vicinities of front ends of the left and rightlink members 15 and between the left and right link members 15. Therotary member 14 is disposed on the upper side of the left and rightlink members 15.

Referring to FIG. 4, the rotary member 14 extends in the vehicle widthdirection so as to have a width equal to that of the handlebar post 11as viewed from above. The rotary member 14 includes: a main body portion14 f located in a front portion of the rotary member 14; and a pair ofleft and right extending portions 14 b extending rearward with apredetermined interval therebetween on the inside in the vehicle widthdirection of the main body portion 14 f. Connecting portions 14 a towhich a left first ball joint 40 and a right first ball joint 40 to bedescribed later are connected are formed in a left end portion and aright end portion of the main body portion 14 f.

Referring also to FIG. 5, an insertion hole 31 h opening in the vehiclewidth direction is formed in the left and right extending portions 14 bof the rotary member 14. In a state of the cylindrical journalingportion 13 d being held between the left and right extending portions 14b, a bolt 31 a is inserted through the insertion holes 31 h and an innercircumference of the journaling portion 13 d, and a nut 31 b is screwedand fastened to a projecting portion of the bolt 31 a. An outercircumference of the bolt 31 a is provided with a pair of left and rightside collars 31 j, a pair of left and right ball bearings 31 g adjacentto the insides of the left and right side collars 31 j, and a centercollar 31 i for securing a distance between the left and right ballbearings 31 g. The journaling portion 13 d of the turning member 13supports the rotary member 14 rotatably about the rotation axis C4 viathe left and right ball bearings 31 g.

Referring also to FIG. 2, FIG. 4, and FIG. 5, the link members 15 areprovided as a pair of left and right members on both sides in thevehicle width direction. As viewed from above, the left and right linkmembers 15 extend linearly in the forward-rearward direction of thevehicle, and are arranged in parallel with each other in the vehiclewidth direction. The front end portions of the left and right linkmembers 15 are connected rotatably about a first axis C5 to be describedlater on the side of the turning member 13, and rear end portions of theleft and right link members 15 are connected rotatably about a secondaxis C6 to be described later on the side of the handlebars 8.

Specifically, the front end portions of the left and right link members15 are connected with a pair of left and right first ball joints 40provided on both sides in the vehicle width direction. The rear endportions of the left and right link members 15 are connected with a pairof left and right second ball joints 43 provided on both sides in thevehicle width direction. The front end portions of the left and rightlink members 15 are rotatably connected to the left and right connectingportions 14 a of the rotary member 14 via the left and right first balljoints 40, and the rear end portions of the left and right link members15 are rotatably connected to the left and right connecting portions 11c of the handlebar post 11 via the left and right second ball joints 43.

The left and right first ball joints 40 each include a first ball stud41 and a first socket 42.

The left and right first ball studs 41 each include a spherical ballportion 41 a and a stud portion 41 b projecting upward from the ballportion 41 a. The left and right ball portions 41 a are slidablyretained within the left and right first sockets 42. The left and rightstud portions 41 b extend linearly in the upward-downward direction ofthe vehicle.

The left and right first sockets 42 each include a first upper socket 42a and a first lower socket 42 b. The ball portion 41 a is slidablyretained between the first upper socket 42 a and the first lower socket42 b.

An insertion hole 14 h opening in the upward-downward direction of thevehicle is formed in the left and right connecting portions 14 a of therotary member 14. Screw portions of upper end portions of the left andright stud portions 41 b are inserted into the left and right insertionholes 14 h, and a nut 32 is screwed and fastened to the upwardprojecting portions of the screw portions, whereby the left and rightstud portions 41 b are fastened and fixed to the left and rightconnecting portions 14 a of the rotary member 14.

Incidentally, a symbol C5 in the figures denotes the central axis of theleft and right stud portions 41 b. The central axis C5 may hereinafterbe referred to as a first axis. The first axis C5 is a straight lineextending in the upward-downward direction of the vehicle. In addition,a symbol C7 in the figures denotes the center of the left and right ballportions 41 a. The center C7 of the left and right ball portions 41 aare a center of rotation of the left and right first ball joints 40.

The left and right second ball joints 43 each include a second ball stud44 and a second socket 45.

The left and right second ball studs 44 each include a spherical ballportion 44 a and a stud portion 44 b projecting upward from the ballportion 44 a. The left and right ball portions 44 a are slidablyretained within the left and right second sockets 45. The left and rightstud portions 44 b are parallel with the left and right stud portions 41b, and extend linearly in the upward-downward direction of the vehicle.

The left and right second sockets 45 each include a second upper socket45 a and a second lower socket 45 b. The ball portion 44 a is slidablyretained between the second upper socket 45 a and the second lowersocket 45 b.

An insertion hole 11 h opening in the upward-downward direction of thevehicle is formed in the left and right connecting portions 11 c of thehandlebar post 11. Screw portions of upper end portions of the left andright stud portions 44 b are inserted into the left and right insertionholes 11 h, and a nut 32 is screwed and fastened to the upwardprojecting portions of the screw portions, whereby the left and rightstud portions 44 b are fastened and fixed to the left and rightconnecting portions 11 c of the handlebar post 11.

Incidentally, a symbol C6 in the figures denotes the central axis of theleft and right stud portions 44 b. The central axis C6 may hereinafterbe referred to as a second axis. The second axis C6 is a straight linethat is parallel with the first axis C5 and which extends in theupward-downward direction of the vehicle. In addition, a symbol C8 inthe figures denotes the center of the left and right ball portions 44 a.The center C8 of the left and right ball portions 44 a is a center ofrotation of the left and right second ball joints 43.

The front end portions of the left and right link members 15 areconnected to rear end portions 42 r of the left and right first lowersockets 42 b, and the rear end portions of the left and right linkmembers 15 are connected to front end portions 45 f of the left andright second lower sockets 45 b. Specifically, the left and right linkmembers 15 are fixed by using a lock nut 33 in a state in which screwportions 15 a of the front end portions of the left and right linkmembers 15 are screwed into the rear end portions 42 r of the left andright first lower sockets 42 b by a predetermined amount, and the leftand right link members 15 are fixed by using a lock nut 33 in a state inwhich screw portions 15 b of the rear end portions of the left and rightlink members 15 are screwed into the front end portions 45 f of the leftand right second lower sockets 45 b by a predetermined amount. Distancesbetween the front and rear connecting portions for the left and rightlink members 15 can be adjusted by loosening the lock nuts 33 andincreasing or decreasing amounts of screwing of the front screw portions15 a and the rear screw portions 15 b into the left and right firstlower sockets 42 b and the left and right second lower sockets 45 b,respectively.

The left and right link members 15 form parallel links together with therotary member 14 and the handlebar post 11 as viewed in the directionalong the steering axis C2 and the steering axis C3. Therefore, thefront wheel 9 can be turned at the same angle as the steering angle ofthe handlebars 8. In addition, the left and right link members 15linearly interlock the steering operation of the handlebars 8 with thesteering operation of the turning member 13.

Referring also to FIG. 2, FIG. 3, and FIG. 9, the front end portion ofthe rocking arm 16 is rockably supported by the head pipe 12, and therear end portion of the rocking arm 16 is rockably supported by thefront block 2. The rocking arm 16 has a pair of upper and lower armportions 17 and 18. The upper and lower arm portions 17 and 18 arearranged in juxtaposition to each other in the upward-downward directionof the vehicle, and extend along the forward-rearward direction of thevehicle.

The front and rear end portions 17 a and 17 b of the upper arm portion17 of the rocking arm 16 are respectively arranged in front of the frontand rear end portions 18 a and 18 b of the lower arm portion 18 of therocking arm 16. The front end portions 17 a of the upper arm portion 17of the rocking arm 16 are supported in front of the steering axis C3,and the front end portions 18 a of the lower arm portion 18 of therocking arm 16 are supported in the rear of the steering axis C3. Thefront end portions 17 a of the upper arm portion 17 of the rocking arm16 are disposed below an upper end of the head pipe 12, and the frontend portions 18 a of the lower arm portion 18 are disposed in thevicinity of a lower end of the head pipe 12.

Referring also to FIG. 6, the front end portions 17 a of the upper armportion 17 are rockably supported via a bolt 34 a as a coupling memberthat penetrates the connecting portion 12 a of the head pipe 12 andwhich extends along the vehicle width direction. The rear end portions17 b of the upper arm portion 17 are rockably supported via a bolt 35 aas a coupling member that penetrates the connecting portions 2 b of thefront block 2 and which extends along the vehicle width direction.

The upper arm portion 17 integrally includes a pair of left and rightarm main bodies 17 c extending longitudinally and a cross member 17 dcoupling the rear end portions 17 b of the left and right arm mainbodies 17 c to each other. The elements of the upper arm portion 17 areeach an integral part made of aluminum, for example. These elements arejoined by welding to be integral with each other.

The left and right arm main bodies 17 c are arranged on both of the leftand right sides of an upper portion of the head pipe 12. The left andright arm main bodies 17 c are curved to the inside in the vehicle widthdirection in such a manner as to be along an outer wall surface of theupper portion of the head pipe 12.

The cross member 17 d extends in the vehicle width direction in the rearof the upper portion of the head pipe 12. Both of end portions of thecross member 17 d are joined to the rear end portions 17 b of the leftand right arm main bodies 17 c.

An insertion hole 34 h opening in the vehicle width direction is formedin the front end portions 17 a of the left and right arm main bodies 17c. In a state of the connecting portion 12 a of the head pipe 12 beingheld between the front end portions 17 a of the left and right arm mainbodies 17 c, the bolt 34 a is passed through the insertion holes 34 hand an inner circumference of the connecting portion 12 a, and isscrewed and fastened to a nut 34 b. An outer circumference of the bolt34 a is provided with a pair of left and right side collars 34 j forsupporting a pair of left and right needle bearings 34 m, a centercollar 34 i for securing a distance between the left and right sidecollars 34 j, and a ball bearing 34 g receiving a thrust via the rightside collar 34 j and the center collar 34 i. The front end portions 17 aof the upper arm portion 17 are rockably supported by the connectingportion 12 a via the left and right side collars 34 j, the center collar34 i, and the ball bearing 34 g.

Incidentally, a symbol C9 in the figures denotes the central axis of thebolt 34 a. The central axis C9 may hereinafter be referred to as a firstcoupling axis. The first coupling axis C9 is disposed between the upperend and the lower end of the head pipe 12 as viewed from the side.

An insertion hole 35 h opening in the vehicle width direction is formedin the left and right connecting portions 2 b of the front block 2. Anadjusting collar 35 k for adjusting a lateral gap is provided in theleft connecting portion 2 b of the front block 2. In a state of the rearend portions 17 b of the upper arm portion 17 (the rear end portions 17b of the left and right arm main bodies 17 c and the cross member 17 d)being held between the left and right connecting portions 2 b of thefront block 2, the bolt 35 a is passed through the insertion holes 35 hand inner circumferences of the rear end portions 17 b of the upper armportion 17, and is screwed and fastened to a nut 35 b. An outercircumference of the bolt 35 a is provided with a pair of left and rightside collars 35 j for supporting a pair of left and right needlebearings 35 m, a center collar 35 i for securing a distance between theleft and right side collars 35 j, and a ball bearing 35 g receiving athrust via the right side collar 35 j and the center collar 35 i. Therear end portions 17 b of the upper arm portion 17 are rockablysupported by the left and right connecting portions 2 b via the left andright side collars 35 j, the center collar 35 i, and the ball bearing 35g.

Incidentally, a symbol C10 in the figures denotes the central axis ofthe bolt 35 a. The central axis C10 may hereinafter be referred to as asecond coupling axis.

Referring also to FIG. 7, the front end portions 18 a of the lower armportion 18 are rockably supported via a bolt 36 a as a coupling memberthat penetrates the connecting portion 12 b of the head pipe 12 andwhich extends along the vehicle width direction. The rear end portions18 b of the lower arm portion 18 are rockably supported via a bolt 37 aas a coupling member that penetrates the connecting portions 2 c of thefront block 2 and which extends along the vehicle width direction.Connecting portions 18 e to which a front lower end portion 20 a of thecushion unit 20 is connected are formed in a front lower portion of thelower arm portion 18.

The lower arm portion 18 integrally includes a pair of left and rightarm main bodies 18 c extending longitudinally and a cross member 18 dcoupling the rear end portions 18 b of the left and right arm mainbodies 18 c to each other. The elements of the lower arm portion 18 areeach an integral part made of aluminum, for example. These elements arejoined by welding to be integral with each other. The longitudinallength of the lower arm portion 18 is larger than the longitudinallength of the upper arm portion 17. Referring to FIG. 2, as viewed fromthe side, a length W2 of a second segment connecting a third couplingaxis C11 to a fourth coupling axis C12 is larger than a length W1 of afirst segment connecting the first coupling axis C9 to the secondcoupling axis C10 (W2>W1).

The left and right arm main bodies 18 c are arranged on both of the leftand right sides of a lower portion of the cushion unit 20. The left andright arm main bodies 18 c are curved to the inside in the vehicle widthdirection in such a manner as to be along an outer circumferentialsurface of the lower portion of the cushion unit 20 (spring 20 f to bedescribed later). Spaces 18 s curved to the inside in the vehicle widthdirection are formed within the left and right arm main bodies 18 c.

The cross member 18 d extends in the vehicle width direction in the rearof the lower portion of the cushion unit 20. Both of end portions of thecross member 18 d are joined to the rear end portions 18 b of the leftand right arm main bodies 18 c.

An insertion hole 36 h opening in the vehicle width direction is formedin the front end portions 18 a of the left and right arm main bodies 18c. In a state of the connecting portion 12 b of the head pipe 12 beingheld between the front end portions 18 a of the left and right arm mainbodies 18 c, a bolt 36 a is passed through the insertion holes 36 h andan inner circumference of the connecting portion 12 b, and is screwedand fastened to a nut 36 b. An outer circumference of the bolt 36 a isprovided with a pair of left and right side collars 36 j for supportinga pair of left and right needle bearings 36 m, a center collar 36 i forsecuring a distance between the left and right side collars 36 j, and aball bearing 36 g receiving a thrust via the right side collar 36 j andthe center collar 36 i. The front end portions 18 a of the lower armportion 18 are rockably supported by the connecting portion 12 b via theleft and right side collars 36 j, the center collar 36 i, and the ballbearing 36 g.

Incidentally, a symbol C11 in the figures denotes the central axis ofthe bolt 36 a. The central axis C11 may hereinafter be referred to as athird coupling axis. The third coupling axis C11 is disposed between theupper end and the lower end of the head pipe 12 as viewed from the side.

An insertion hole 37 h opening in the vehicle width direction is formedin the left and right connecting portions 2 c of the front block 2. Anadjusting collar 37 k for adjusting a lateral gap is provided to theleft connecting portion 2 c of the front block 2. In a state of the rearend portions 18 b of the lower arm portion 18 (the rear end portions 18b of the left and right arm main bodies 18 c and the cross member 18 d)being held between the left and right connecting portions 2 c of thefront block 2, a bolt 37 a is passed through the insertion holes 37 hand inner circumferences of the rear end portions 18 b of the lower armportion 18, and is screwed and fastened to a nut 37 b. An outercircumference of the bolt 37 a is provided with a pair of left and rightside collars 37 j for supporting a pair of left and right needlebearings 37 m, a center collar 37 i for securing a distance between theleft and right side collars 37 j, and a ball bearing 37 g receiving athrust via the right side collar 37 j and the center collar 37 i. Therear end portions 18 b of the lower arm portion 18 are rockablysupported by the left and right connecting portions 2 c via the left andright side collars 37 j, the center collar 37 i, and the ball bearing 37g.

Incidentally, a symbol C12 in the figures denotes the central axis ofthe bolt 37 a. The central axis C12 may hereinafter be referred to as afourth coupling axis.

In addition, as viewed from the side in FIG. 2, a bead shape 12 e isformed between the connecting portion 12 a and the connecting portion 12b of the head pipe 12. The bead shape 12 e is formed along a segmentconnecting the first coupling axis C9 to the third coupling axis C11.

In addition, a symbol AX1 in the figures denotes a first straight linepassing through the first coupling axis C9 and the second coupling axisC10 as viewed from the side. A symbol AX2 in the figures denotes asecond straight line passing through the third coupling axis C11 and thefourth coupling axis C12 as viewed from the side.

In the 1G state in the figures, the first straight line AX1 of the upperarm portion 17 and the second straight line AX2 of the lower arm portion18 are parallel with each other.

Referring also to FIG. 2, FIG. 6, FIG. 7, and FIG. 9, the front lowerend portion 20 a of the cushion unit 20 is rockably connected to thelower arm portion 18, and the rear upper end portion 20 b of the cushionunit 20 is rockably connected to the supporting portion 2 a. The cushionunit 20 provides a cushioning action by making the front lower endportion 20 a perform a stroke as the lower arm portion 18 rocks.

The cushion unit 20 includes a damper 20 e and a spring 20 f.

The damper 20 e is a rod type damper inclined such that an upper side ofthe damper is located more rearward than a lower side of the damper asviewed from the side.

The spring 20 f is a coil spring wound around the damper 20 e.

The cushion unit 20 expands and contracts by performing a stroke alongthe central axis C15 of the cushion unit 20, and thereby provides apredetermined cushioning action. The central axis C15 may hereinafter bereferred to as a stroke axis.

Referring also to FIG. 2 and FIG. 9, the front lower end portion 20 a ofthe cushion unit 20 is supported in front of a middle point Pm of thesegment connecting the third coupling axis C11 to the fourth couplingaxis C12 as viewed from the side, and the rear upper end portion 20 b ofthe cushion unit 20 is supported in the rear of the second coupling axisC10 as viewed from the side.

The front lower end portion 20 a of the cushion unit 20 is located infront of the longitudinal middle position of the lower arm portion 18.The front lower end portion 20 a of the cushion unit 20 is located infront of the middle point Pm of the segment connecting the thirdcoupling axis C11 to the fourth coupling axis C12 as viewed from theside, and is located below the segment.

The rear upper end portion 20 b of the cushion unit 20 is located in thevicinity of a lower end of the shaft portion 11 a of the handlebar post11 forming the steering axis C2, and in the rear of and below thesteering axis C2 as viewed from the side. The rear upper end portion 20b of the cushion unit 20 is located in the rear of the rear end portions17 b of the upper arm portion 17.

The rear upper end portion 20 b of the cushion unit 20 is disposed inthe rear of the fourth coupling axis C12 as viewed from the side.Specifically, the rear upper end portion 20 b of the cushion unit 20 islocated above and in the rear of the rear end portions 18 b of the lowerarm portion 18.

Referring to FIG. 7, an insertion hole 39 h opening in the vehicle widthdirection is formed in the left and right connecting portions 18 e ofthe lower arm portion 18. In a state of the front lower end portion 20 aof the cushion unit being held between the left and right connectingportions 18 e of the lower arm portion 18, a bolt 39 a is insertedthrough the insertion holes 39 h and an inner circumference of the frontlower end portion 20 a of the cushion unit, and a nut 39 b is screwedand fastened to the projecting portion of the bolt 39 a. An outercircumference of the bolt 39 a is provided with a collar 39 j forsupporting a needle bearing 39 m. The front lower end portion 20 a ofthe cushion unit 20 is rockably supported by the left and rightconnecting portions 18 e via the collar 39 j.

Incidentally, a symbol C13 in the figures denotes the central axis ofthe bolt 39 a.

Referring to FIG. 6, an insertion hole 38 h opening in the vehicle widthdirection is formed in the left and right connecting portions 2 e of thesupporting portion 2 a. In a state of the rear upper end portion 20 b ofthe cushion unit being held between the left and right connectingportions 2 e of the supporting portion 2 a, a bolt 38 a is insertedthrough the insertion holes 38 h and an inner circumference of the rearupper end portion 20 b of the cushion unit, and a nut 38 b is screwedand fastened to the projecting portion of the bolt 38 a. An outercircumference of the bolt 38 a is provided with a collar 38 j forsupporting a needle bearing 38 m. The rear upper end portion 20 b of thecushion unit 20 is rockably supported by the left and right connectingportions 2 e via the collar 38 j.

Incidentally, a symbol C14 in the figures denotes the central axis ofthe bolt 38 a.

FIG. 1 and FIG. 9 show the 1G state in which the load of the vehicleweight is applied to the front wheel suspension device 10.

When front wheel braking or the like displaces the front wheel 9relatively upward from this state, the rocking arm 16 rocks upward, andthus the front fork 19 and the head pipe 12 are displaced upward. Atthis time, the lower arm portion 18 rotates backward in a right-handeddirection (clockwise direction) about the fourth coupling axis C12.Then, the lower arm portion 18 displaces the front lower end portion 20a of the cushion unit 20 upward, and thus compresses the cushion unit20.

When the head pipe 12 is displaced upward, the turning member 13 is alsointegrally displaced in accordance with the displacement of the headpipe 12. At this time, the rotary member 14 is displaced with respect tothe handlebar post 11, and the angle of the steering axis C3 to thesteering axis C2 is changed. However, this change is accommodated by therocking of the left and right first ball joints 40 and the left andright second ball joints 43 and the rotation of the rotary member 14.

On the other hand, when acceleration or the like displaces the frontwheel 9 relatively downward from the 1G state, the rocking arm 16 rocksdownward, and thus the front fork 19 and the head pipe 12 are displaceddownward. At this time, the lower arm portion 18 rotates forward in aleft-handed direction (counterclockwise direction) about the fourthcoupling axis C12. Then, the lower arm portion 18 displaces the frontlower end portion 20 a of the cushion unit 20 downward, and thus extendsthe cushion unit 20.

When the head pipe 12 is displaced downward, the turning member 13 isalso integrally displaced in accordance with the displacement of thehead pipe 12. At this time, the rotary member 14 is displaced withrespect to the handlebar post 11, and the angle of the steering axis C3to the steering axis C2 is changed. However, this change is accommodatedby the rocking of the left and right first ball joints 40 and the leftand right second ball joints 43 and the rotation of the rotary member14.

As described above, the foregoing embodiment is a front suspensionstructure for a saddle riding type vehicle, the front suspensionstructure including: a head pipe 12 radially internally supporting ashaft portion 13 b forming a steering axis C3 such that the shaftportion 13 b is rotatable about the steering axis C3; a front fork 19connected to a lower end portion of the shaft portion 13 b on a lowerside of the head pipe 12, the front fork 19 supporting an axle 9 a of asteering wheel 9; a link 15 having one end portion connected rotatablyon an upper side of a turning member 13 having the shaft portion 13 b,and having another end portion connected rotatably on a side ofhandlebars 8; the head pipe 12 being disposed so as to be separatedfrontward from a vehicle body frame 1; a rocking arm 16 having a frontend portion rockably supported by the head pipe 12, and having a rearend portion rockably supported by the vehicle body frame 1.

According to this constitution, the front end portion of the rocking arm16 is supported by the head pipe 12 on the outside in the radialdirection of the shaft portion 13 b forming the steering axis C3. Thus,the position at which the rocking arm 16 is supported can be setarbitrarily. Hence, a degree of freedom of the position at which the armportion is supported can be increased. In addition, because a turningsystem of the turning member 13 and the like and a rocking system of therocking arm 16 and the like are separated from each other, the turningsystem is not readily affected by rocking.

In addition, in the foregoing embodiment, the rocking arm 16 includes anupper arm portion 17 and a lower arm portion 18 vertically separatedfrom each other, the head pipe 12 is inclined such that an upper side ofthe head pipe 12 is located more rearward than a lower side of the headpipe 12 as viewed from a side, a front end portion 17 a of the upper armportion 17 is in front of the steering axis C3 and is supported by afront upper portion of the head pipe 12, and a front end portion 18 a ofthe lower arm portion 18 is in a rear of the steering axis C3 and issupported by a rear lower portion of the head pipe 12. Thus, spaces ofthe front upper portion and the rear lower portion of the head pipe 12which spaces are created by the inclination of the head pipe 12 can beutilized effectively as spaces for supporting the respective front endportions 17 a and 18 a of the upper and lower arm portions 17 and 18. Itis therefore possible to make the front suspension structure compact andthus shorten an overall length of the front suspension structure. Inaddition, because the respective front end portions 17 a and 18 a of theupper and lower arm portions 17 and 18 are distributed longitudinally,the concentration of force on one part can be prevented.

In addition, in the foregoing embodiment, the front end portion 17 a ofthe upper arm portion 17 and the front end portion 18 a of the lower armportion 18 are rockably supported via coupling members 34 a and 36 a,respectively, the coupling members 34 a and 36 a penetrating connectingportions 12 a and 12 b of the head pipe 12 and extending along a vehiclewidth direction. Thus, the upper and lower arm portions 17 and 18 can besupported by the respective coupling members so as to avoid the headpipe 12. Therefore the respective front end portions 17 a and 18 a ofthe upper and lower arm portions 17 and 18 can be supported with highrigidity.

In addition, in the foregoing embodiment, the front end portion 17 a ofthe upper arm portion 17 and the front end portion 18 a of the lower armportion 18 are connected respectively to connecting portions 12 a and 12b of the head pipe 12 rockably about coupling axes C9 and C11 along thevehicle width direction, and at least one of the coupling axes C9 andC11 is disposed between an upper end and a lower end of the head pipe 12as viewed from the side. Thus, the respective front end portions 17 aand 18 a of the upper and lower arm portions 17 and 18 can be supportedon the head pipe 12 compactly.

It is to be noted that the foregoing embodiment has been described byciting an example in which the first straight line AX1 of the upper armportion 17 and the second straight line AX2 of the lower arm portion 18are parallel with each other in the 1G state. However, the presentinvention is not limited to this.

For example, rearward extension parts of the first straight line AX1 ofthe upper arm portion 17 and the second straight line AX2 of the lowerarm portion 18 may intersect each other such that the first straightline AX1 of the upper arm portion 17 and the second straight line AX2 ofthe lower arm portion 18 are separated from each other more toward thefront in the 1G state. For such an intersection arrangement, forexample, it is preferable to shift the vertical position of the secondcoupling axis C10 downward or shift the vertical position of the fourthcoupling axis C12 upward as viewed from the side.

In addition, frontward extension parts of the first straight line AX1 ofthe upper arm portion 17 and the second straight line AX2 of the lowerarm portion 18 may intersect each other such that the first straightline AX1 of the upper arm portion 17 and the second straight line AX2 ofthe lower arm portion 18 are separated from each other more toward therear in the 1G state. For such an intersection arrangement, for example,it is preferable to shift the vertical position of the second couplingaxis C10 upward or shift the vertical position of the fourth couplingaxis C12 downward as viewed from the side.

In addition, the foregoing embodiment has been described by citing anexample in which the steering axis C3 is separated frontward from thesteering axis C2 and the steering axis C3 and the steering axis C2 areparallel with each other in the 1G state. However, the present inventionis not limited to this. For example, the steering axis C3 may beseparated frontward from the steering axis C2, and the steering axis C3and the steering axis C2 may intersect each other. That is, it sufficesfor the steering axis C3 to be separated frontward from the steeringaxis C2.

In addition, the foregoing embodiment has been described by citing anexample in which the first axis C5 is a straight line extending in theupward-downward direction of the vehicle and the second axis C6 is astraight line that is parallel with the first axis C5 and which extendsin the upward-downward direction of the vehicle. However, the presentinvention is not limited to this. For example, the first axis C5 may bea straight line along a direction intersecting the vehicle widthdirection, and the second rocking straight line C6 may be a straightline that is along a direction intersecting the vehicle width directionand which is different from the first axis C5.

In addition, the foregoing embodiment has been described by citing anexample in which each of the first coupling axis C9 and the thirdcoupling axis C11 is disposed between the upper end and the lower end ofthe head pipe 12 as viewed from the side. However, the present inventionis not limited to this. For example, only the first coupling axis C9 maybe disposed between the upper end and the lower end of the head pipe 12as viewed from the side, or only the third coupling axis C11 may bedisposed between the upper end and the lower end of the head pipe 12 asviewed from the side. That is, it suffices for at least one of the firstcoupling axis C9 and the third coupling axis C11 to be disposed betweenthe upper end and the lower end of the head pipe 12 as viewed from theside.

It is to be noted that the present invention is not limited to theforegoing embodiment. For example, the saddle riding type vehicledescribed above includes vehicles in general that drivers ride astridevehicle bodies thereof. The saddle riding type vehicle described aboveincludes not only motorcycles (including motor-assisted bicycles andmotor scooter type vehicles) but also three-wheeled vehicles (includingvehicles having two front wheels and one rear wheel as well as vehicleshaving one front wheel and two rear wheels).

In addition, the present invention may be applied to vehicles having alongitudinally mounted engine other than a horizontally opposed engineand vehicles having a laterally mounted engine with a crankshaft alongthe vehicle width direction. The present invention may also be appliedto constitutions in which a cushion unit or a cushion arm is supportedby an engine as a vehicle body.

The constitution in the foregoing embodiment is an example of thepresent invention, and is susceptible of various changes withoutdeparting from the spirit of the present invention by replacing aconstituent element in the embodiment with a well-known constituentelement, for example.

We claim:
 1. A front suspension structure for a saddle riding typevehicle, the front suspension structure comprising: a head pipe radiallyinternally supporting a shaft portion forming a steering axis such thatthe shaft portion is rotatable about the steering axis; a front forkconnected to a lower end portion of the shaft portion on a lower side ofthe head pipe, the front fork supporting an axle of a steering wheel;and a link member having one end portion connected rotatably on an upperside of a turning member having the shaft portion, and having anotherend portion connected rotatably on a side of handlebars; the head pipedisposed so as to be separated frontward from a vehicle body frame; arocking arm having a front end portion rockably supported by the headpipe, and having a rear end portion rockably supported by the vehiclebody frame.
 2. The front suspension structure for the saddle riding typevehicle according to claim 1, wherein the rocking arm includes an upperarm portion and a lower arm portion vertically separated from eachother, the head pipe is inclined such that an upper side of the headpipe is located more rearward than a lower side of the head pipe asviewed from a side, a front end portion of the upper arm portion is infront of the steering axis and is supported by a front upper portion ofthe head pipe, and a front end portion of the lower arm portion is in arear of the steering axis and is supported by a rear lower portion ofthe head pipe.
 3. The front suspension structure for the saddle ridingtype vehicle according to claim 2, wherein the front end portion of theupper arm portion and the front end portion of the lower arm portion arerockably supported via coupling members, respectively, the couplingmembers penetrating connecting portions of the head pipe and extendingalong a vehicle width direction.
 4. The front suspension structure forthe saddle riding type vehicle according to claim 2, wherein the frontend portion of the upper arm portion and the front end portion of thelower arm portion are connected respectively to connecting portions ofthe head pipe rockably about coupling axes along the vehicle widthdirection, and at least one of the coupling axes is disposed between anupper end and a lower end of the head pipe as viewed from the side. 5.The front suspension structure for the saddle riding type vehicleaccording to claim 3, wherein the front end portion of the upper armportion and the front end portion of the lower arm portion are connectedrespectively to the connecting portions of the head pipe rockably aboutcoupling axes along the vehicle width direction, and at least one of thecoupling axes is disposed between an upper end and a lower end of thehead pipe as viewed from the side.